On the contrary; it's quite possible to design automated tests that operate on release artifacts. This is true not only at the integration level (testing the external interfaces of the artifact in a black-box manner), but also at a more granular level; e.g., running lower-level unit tests in your code's dependency structure.

It's true that not all tests which are possible to run in debug configuration can also be run on a release artifact; e.g. if there are test-only interfaces that are compiled out in the release configuration.

I think maybe the source of the confusion in this conversation is perhaps the kind of artifact being tested? For example, if I were developing ffmpeg, to choose an arbitrary example, I would absolutely have tests which operate on the production artifact -- the binary compiled in release mode -- which only exercise public interfaces of the tool; e.g. a test which transcodes file A to file B and asserts correctness in some way. This kind of test should be absolutely achievable both in dev builds as well as when testing the deliverable artifact.